Supporters stand in front of large photos of Shiv Sena chief Bal Thackeray outside his residence in Mumbai, India, Thursday. News that Thackery may be critically ill lead to a surge of supporters in thousands outside his residence.

New York — Reports that controversial right-wing leader Bal Thackeray was critically ill put Mumbai on tense hold for much of Thursday while raising questions about the future of his party, the Shiv Sena, which controls the city government and is an important member of India’s opposition group, the BJP-led National Democratic Alliance.

Parts of Mumbai reportedly shut down Thursday in anticipation of trouble from Sainiks, as the members of his party are known, gathered in large numbers near the residence of the Thackerays. By evening, the 86-year-old’s condition was reported to be stable and a parade of the city’s powerful and famous was visiting the leader’s home amid tight security.

Thackeray's declining health is putting the spotlight on the fragile state of his party, which has been riddled by succession struggles for more than a decade and has seemed unable to move beyond its founder’s polarizing identity politics.

In the four decades of its existence, the Shiv Sena has targeted – sometimes violently – south Indian migrants to the city, Muslims, so-called symbols of Western culture like Valentine’s Day, and more recently, north Indian migrants. Earlier this month, Mr. Thackeray reiterated his opposition to cricket matches between the Indian and Pakistani teams in a front-page editorial in the party newspaper,Saamna, asking party activists to stop such matches from being held in the country.

Shiva's Army

A political cartoonist known for his barbed rhetoric, Mr. Thackeray formed the Shiv Sena (Shiva’s Army) in the 1960s in the wake of the successful movement for the formation of the state of Maharashtra with Mumbai as its capital. Not unlike Tammany Hall in New York, the Sena promoted the interests of local Maharashtrians or “sons of the soil” against the influx of migrant workers to Mumbai, historically India’s most cosmopolitan city and its commercial headquarters, through a network of street cadres.

The Sena’s power grew in the 1970s and 1980s, at the expense of the Communists. Thackeray’s invocation of a proud, native identity especially through the historical figure of Shivaji, a 17th century Hindu Maratha warrior who fought the Muslim Mughals and established a Hindu kingdom, found resonance with disaffected young men at a time of declining industrial jobs. During the ‘80s and ‘90s, the party members’ rough-and-ready tactics gave Thackeray the power to shut down the city.

The Sena found broader electoral power in the mid-1990s when it allied with the Hindu nationalist Bharatiya Janata Party to win the state and later participate in the BJP-led coalition government at the center. Thackeray never held political office but famously said in 1995 that he had “remote control” of the state government. Thackeray was indicted by an independent commission for inciting hatred against Muslims during communal riots in 1993, but he was never brought to trial.

Power waning

Since the late 1990s, however, the party has struggled to maintain relevance in a globalizing city and in the absence of fresh ideas and a viable second-rung leadership.

Thackeray anointed his relatively peaceable son, Uddhav, as party leader in 2004, over his more popular nephew Raj, who then split to found his own party in 2006, the Maharashtra Navnirman Sena. The MNS is seen as hewing more closely to the ideological and combative spirit of Bal Thackeray. In 2008, MNS members attacked north Indians who had come to the city for an entrance exam for government jobs.

Given its decline, the Sena party surprised observers earlier this year when its candidates swept city elections with the aid of an alliance with the Republican Party of India, which represents lower-caste Dalits.

The win doesn’t necessarily portend the re-emergence of the party beyond its stronghold of Mumbai, however.

The gains, suggested veteran journalist and political observer Kumar Ketkar in a column, are a “recognition of the political and cultural reality of this growing metropolis, where the single-largest bloc feels it is being marginalized.” An editorial in the Economic Times noted that with the city widely felt to be in decline, the win was an opportunity for the Sena “to deepen and widen the party's appeal through honest and efficient civic governance.”

Whether Thackeray’s illness will bring the son and nephew back together, as some observers suggest may happen, could now determine the survival of his party